1. Field of the Invention
This invention relates generally to a crawler pad for the tread board of a crawler track shoe. More specifically, this invention concerns a crawler pad for protecting a road surface from the endless track of a vehicle which carries various machinery for construction, civil and agricultural engineering, etc.
2. Description of the Prior Art
It has been known that a crawler pad is fitted to the tread board of a crawler track shoe to protect the surface of a road from the endless track of a vehicle on which such a machine for construction is mounted. The old crawler pad, on which serious abrasion has occurred due to heavy weight of vehicles and severe onsite operating conditions, needs to be replaced with a new one.
Recently, there have been some proposals to make it easy to replace an old crawler pad with a new one. As a typical example, a crawler pad includes a metal core; a fixed hook rigidly secured to one end of the metal core and a detachable hook detachably secured to the other end of the same. It is necessary that the detachable hook can be easily secured to and detached from the metal core, whenever it is needed. As a conventional means for detachably securing a detachable hook to a metal core, Japanese unexamined patent publication No. 34085/93 and No. 191447/94 disclose that a detachable hook is screwed to a metal core by means of a bolt. Further, it is known to use a lock pin (Japanese unexamined patent publication No. 58647/96) or a slide lock (Japanese unexamined patent publication No. 119847/98) instead of the bolt. However, these securing means such as a bolt, a lock pin and a slide lock are likely to come loose and come off due to violent vibration of long duration.
Also, in the prior art, as an attempt to improve the problem as set forth above, Japanese unexamined patent publication No. 301233/97 has been known. In this invention, a metallic socket includes a hook part for holding a tread board and an inserting part for a rubber pad. The socket is applied to fasten them in such a manner that after inserting the inserting part into the slot of the rubber pad, a bolt is screwed into the holes of the inserting part and the tread board. But, in the case where the bolt is embedded in the rubber pad, it is very difficult to come off the bolt, when the rubber pad is replaced.
There are more complicated means for assembling the rubber pad and the tread board in place as disclosed in Japanese unexamined patent publication No. 136678/97, No. 80984/93 and No. 47091/94. They could not be available in practical use, as they are expensive.
An object of the invention is to provide a simple crawler pad that overcomes the drawbacks as set forth above and enables one to easily replace old crawler pads with new ones by means of a device that permits a detachable hook to be firmly secured to and readily detached from a metal core.
In order to accomplish the above-mentioned and other objects, a crawler pad for the tread board of a crawler track shoe according to this invention comprises a pad body made of elastic material, a metal core buried in the pad body and is provided with a locking member having ratchet teeth consisting of at least one row of teeth on its one surface, a fixed hook of which one end is rigidly secured to one end portion of the metal core and the other end is adapted to hold the tread board, a detachable hook of which one end surface facing the locking member has ratchet teeth consisting of-at least one row of teeth to intermesh with the ratchet teeth of the locking member and the other end is adapted to hold the tread board, the ratchet teeth on the locking member and the detachable hook being inclined to permit the detachable hook to slide in its inserting direction and intermesh with one another in its withdrawing direction, thereby allowing the crawler pad on the tread board to be easily replaced when it is requested.
The locking member preferably has engaging margins protruded from its opposite side edges. It is loosely fitted in an opening of one end portion of the metal core, so as to move upwardly and downwardly to the extent that the engaging margins of the locking member are engaged with the corresponding side edges of the opening. Alternatively, the locking member can be loosely fitted in the opening of a holding plate fixed to the one end portion of the metal core.
It is desirable that the ratchet teeth on the locking member and the detachable hook comprise plural rows of teeth, respectively.
Further, the detachable hook has a groove for inserting a releasing pin on its surface where the ratchet teeth are formed. The releasing pin is operable to unlock intermeshing between the ratchet teeth of the locking member and the detachable hook.
A resilient piece is preferably placed between one end face of the metal core and the corresponding face of the detachable hook to bias the detachable hook in its withdrawing direction.
According to another aspect of this invention, a crawler pad for the tread board of a crawler track shoe comprising a pad body made of elastic material, a metal core buried in the pad body, a holding plate fixed to one end of the metal core, a locking member having ratchet teeth consisting of plural rows of teeth on its one surface and engaging margins protruded from its opposite side edges, the locking member being loosely fitted in the opening of the holding plate so as to move upwardly and downwardly to the extent that the engaging margins of the locking member are engaged with corresponding side edges of the opening, a fixed hook of which one end is rigidly secured to the other end portion of the metal core and the other end is adapted to hold the tread board, a detachable hook of which one end has ratchet teeth consisting of plural rows of teeth on the surface thereof to intermesh with the ratchet teeth of the locking member and the other end is adapted to hold the tread board, having a groove for inserting a releasing pin on its surface where the ratchet teeth are formed, the releasing pin being operable to unlock intermeshing between both ratchet teeth on the locking member and the detachable hook, a resilient piece between one outer end face of the metal core and corresponding face of the detachable hook to bias the detachable hook in its withdrawing direction, the ratchet teeth on the locking member and the detachable hook being inclined to permit the detachable hook to slide in its inserting direction and to intermesh with one another in its withdrawing direction, thereby allowing the crawler pad on the tread board to be easily replaced when it is requested.